This invention relates generally to information distribution, and more particularly to distributing information using a broadcast channel and a bi-directional communication channel.
Recent advancements in modem and computer technology allow large amount of digital data to be transmitted electronically. A number of information providers (such as newspaper and magazine publishers) and on-line information distributors have formed partnerships to deliver newspaper and other information on-line. In this system, a subscriber uses a computer and a modem to connect, through a regular phone line, to the computer of an on-line information provider. The subscriber can retrieve information, including newspaper articles, stored in the computer of the information provider.
On-line delivery of newspaper has many advantages. For example, the information can be updated throughout the day while the printed version is printed only once or twice a day. Further, it is possible to do text-based searches on the information. However, it is found that on-line deliver of newspaper and other information is slow. For example, a subscriber has to wait many seconds for a newspaper article to be delivered. The quality of the electronic newspaper is low. For example, in order to reduce storage and communication requirements, graphic images appeared in the printed version are not universally supplied in the on-line version of newspaper. One of the reasons for such poor performance is the limited bandwidth of communication channels used by on-line information distributors. Another reason is that information is centrally processed by the computer at the site of the information distributor, with the result that each subscriber only gets a small slice of the time of the computer.
The present invention uses two channels to deliver digital information: a broadcast channel and a bidirectional channel. The broadcast channel is used to deliver the bulb of the digital information to subscribers. The amount of information delivered is preferably sufficient to satisfy the needs of a large number of subscribers so that they do not have to obtain additional information using the bi-directional channel. The broadcasted information is stored on fast storage media located at subscriber sites. As a result, search and retrieval of the broadcasted information is quick. Further, the broadcasted information is processed locally using a dedicated on-site processor instead of relying on the computers of the information distributors. As a result, the load on the computers of the information distributors is reduced. If the subscribers desire to receive additional information relating to the broadcasted information, the bidirectional communication channel is used to transmit the request and the requested information.
The distribution costs of broadcast channels are typically much lower than that of a bi-directional communication channel. Consequently, the major portion of information is delivered using low cost distribution channels. For a large number of subscribers, the broadcasted information will provide all the information they normally need. Thus, expensive bi-directional communication channels are used only occasionally.
These and other features and advantages of the present invention will be fully understood by referring to the following detailed description in conjunction with the accompanying drawings.